Photodetectors wherein the light absorptive layer is composed of an InGaAs alloy are finding increasing application in the optoelectronics industry. The growth of properly lattice-matched InGaAs (In.sub.0.53 Ga.sub.0.47 As) by vapor phase epitaxy requires precise control of variables such as reactive gas flow rates, carrier gas flow rates, temperatures of source metals, substrate temperature and the like. If a layer of an allou such as InGaAs is not properly lattice-matched to those layers underlying and overlying it in a device, there can be excessive dark currents in the alloy layer and, if the mismatch is severe, stress-induced cracking of the structure.
It has been observed that, heretofore, there has been a depth compositional gradient within a layer of a complex III-V alloy, particularly a ternary or quaternary alloy such as InGaAs, grown by conventional vapor phase epitaxy. As stated above, this compositional gradient, depending on its severity, can be disadvantageous to any device incorporating the layer. In accordance with this invention, a means of eliminating this depth compositional gradient is provided.